|Publication number||US7363851 B2|
|Application number||US 11/336,220|
|Publication date||Apr 29, 2008|
|Filing date||Jan 20, 2006|
|Priority date||Jan 20, 2006|
|Also published as||CA2637650A1, CA2637650C, CN101371051A, CN101371051B, CN102913504A, CN102913504B, EP1979628A1, US20070169622, WO2007087176A1|
|Publication number||11336220, 336220, US 7363851 B2, US 7363851B2, US-B2-7363851, US7363851 B2, US7363851B2|
|Inventors||Ernest George Souliere, Kenneth Alan Blade, Dennis Eugene O'Hara|
|Original Assignee||Fisher Controls International, Llc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Non-Patent Citations (2), Classifications (10), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present disclosure relates generally to actuators and, more specifically, to spacers for use with actuator casings.
Process control systems often employ pneumatic actuators to operate fluid valves as well as other process control devices. Pneumatic actuators typically include a spring casing having upper and lower casing halves between which a diaphragm is captured. An actuator shaft or rod is typically coupled to the diaphragm so that movements of the diaphragm cause corresponding movements of the actuator rod. In turn, if the actuator rod is coupled to, for example, a fluid valve, the movements of the actuator rod may be used to control the position of a fluid flow control member (e.g., a plug) within the valve and, thus, the fluid flowing through the valve.
One or more springs within the spring casing bias the diaphragm and the actuator rod toward a known position and pressurized air may be applied to one side of the diaphragm via a port in one of the casing halves to move the diaphragm and actuator rod against the forces applied by the spring(s). Thus, the springs provide a return force to enable bi-directional movement and control (e.g., open/close control, modulating control, etc.) of the diaphragm and actuator rod positions via a single pressure signal to the actuator.
Typically, the spring casing of a pneumatic actuator includes upper and lower casing halves that are made of stamped, forged, or cast metal. Each of the casing halves typically has an internal cavity with a depth or height that enables the assembled casing halves to accommodate the height of the springs in a desired biased (i.e., partially compressed) condition within the assembled spring casing. Thus, as larger, more powerful springs are needed to satisfy certain applications, the length of the springs needed tends to increase, which requires an increased depth or height of the internal cavities within the casing halves. However, simply increasing the depth or height of the internal cavities within the casing halves can be problematic. For example, in the case where a stamping, forging, or casting process is used to fabricate casing halves, the depth of the casing halves cannot be increased without practical limitation. In particular, as the desired depth of a casing increases, the cost of manufacturing the casing may increase and may become cost prohibitive. Alternatively or additionally, beyond a certain casing depth, it may not be possible to use a stamping, forging, or casting process to fabricate the casing halves. For example, beyond a certain depth or height, it may not be possible to easily remove a casing half from the tool used to fabricate the casing half. In other words, the tool may be jammed when the casing half becomes stuck on the tool.
In one example embodiment, a spacer for use with an actuator casing includes a ring-shaped member defining a central opening and configured to form a part of an actuator casing and to space first and second actuator casing portions a predetermined distance when the first and second casing portions are coupled to the ring-shaped member. The ring-shaped member includes a first surface surrounding the central opening configured to engage the first casing portion and a second surface surrounding the central opening configured to engage the second casing portion. Each of the first and second surfaces includes a plurality of apertures configured to receive threaded fasteners to attach the first and second actuator casing portions to the ring-shaped member.
In another example embodiment, a spacer for use with an actuator casing includes a cylindrical portion having a first end, a second end, and a longitudinal passage extending between the first and second ends. The spacer further includes a first flange adjacent to the first end and a second flange adjacent to the second end. The first flange includes a plurality of threaded apertures, each of which is opposite a respective aperture in the second flange.
In yet another example embodiment, an actuator casing includes a first casing portion, a second casing portion, and a spacer coupled between the first and second casing portions. The spacer includes a plurality of threaded apertures configured to receive fasteners extending through the first and second casing portions.
The example spacers described herein may be advantageously used within actuator casings to enable the cost effective manufacture of, for example, a spring casing having an internal cavity or chamber with a depth or height that accommodates longer, more powerful springs than those typically used with known spring-biased actuators (e.g., spring return pneumatic actuators).
In general, the example spacers described herein include one or more cylindrical and/or ring-shaped members or bodies made substantially of metal or plastic and having apertures configured to receive threaded fasteners such as, for example, threaded rods, bolts, and/or internally threaded members or inserts. Also, generally, the apertures are aligned with corresponding holes or apertures in first (e.g., upper) and second (e.g., lower) actuator casing portions. In this manner, a spacer may be disposed between the first and second casing portions, the apertures of the first casing portion, the second casing portion, and the spacer may be aligned, and threaded fasteners may be used in the apertures to couple the casing portions to the spacer to form a spring casing having an internal cavity with a height or depth greater than may otherwise be achievable using only known upper and lower casings fabricated via known stamping, forging, or casting processes.
In the case where the ring-shaped or cylindrical bodies or members are made substantially of metal, the threaded apertures therein may be formed directly from the metal ring-shaped body or member. However, in the case where the ring-shaped or cylindrical bodies or members are made substantially of plastic, the threaded apertures therein may be formed using threaded metal inserts that are insert-molded (i.e., molded together) with the plastic body or which are inserted into openings in the plastic body after the plastic body is molded or otherwise formed.
The free length (i.e., uncompressed length) of the springs used within an actuator casing may be significantly greater than the depth or height of the internal cavity of a fully assembled actuator spring casing. As a result, it is desirable to configure the spring casing in a manner that permits safe assembly and disassembly of the actuator casing (e.g., in the case that field service of the actuator casing is desirable). Thus, the spacers disclosed herein enable a spring casing to be assembled so that the springs can be slowly compressed from their free length to a preloaded condition as the spring casing portions and spacer are drawn together to form the assembled actuator casing. Likewise, the spacers disclosed herein enable the spring casing to be disassembled (e.g., in the field for servicing) in a manner that permits the springs to be slowly decompressed or unloaded to a substantially uncompressed condition before the actuator casing portions can separate. In other words, the spacers described herein enable an actuator spring casing to be assembled and disassembled in a safe manner that prevents the possibility of a sudden release of spring energy via, for example, a sudden separation of the casing portions while one or more springs are in a compressed condition.
Now turning to
As shown in
The example actuator 100 further includes a first or upper spring plate 122 and a second or lower spring plate 124 between which springs 126 are captured. A diaphragm 128 lies adjacent to the upper spring plate 122 and is sealingly captured between the upper casing 106 and the spacer 102. An actuator shaft or rod 130 is coupled to the upper spring plate 122 and the diaphragm 128 so that movement of the diaphragm 128 and the spring plate 122 causes a corresponding movement of the actuator rod 130. In the example of
The application of a pressure signal (e.g., pressurized air) to a port 132 may be used to increase the pressure in a chamber 134 to move the diaphragm 128, the spring plate 122, and the actuator rod 130 away from the upper casing 106 against the force of the springs 126 (i.e., the springs 126 are further compressed). As the actuator rod 130 extends downward or away from the casing 106, the rod 130 rotates a valve shaft 136 via a linkage 138.
Turning in more detail to the example spacer 102,
Each of the ring-shaped members 140, 142, 144, and 146 includes a plurality of apertures configured to receive the fasteners 110 and 114. The apertures are circumferentially spaced about the ring-shaped members 140, 142, 144, and 146. Additionally, the apertures of each of the ring-shaped members 140, 142, 144, and 146 are coaxially aligned with the apertures of the other ring-shaped members 140, 142, 144, and 146 to enable the fasteners 110 and 114 to pass through the ring-shaped members 140, 142, 144, and 146 as depicted in
To assemble the actuator 100, the nuts 116 and 118 are counter-tightened or locked against each other at one end of the threaded rod 114. One or more additional threaded rods (not shown) are similarly fitted with counter-tightened nuts. The threaded rods (e.g., the rod 114) have a length that enables the rods to extend through the casings 106 and 108 and the spacer 102 when the springs 126 are in a free or uncompressed state. Nuts (e.g., the nut 120) are threaded onto the ends (e.g., the end 148) of the rods (e.g., the rod 114) and then each of the nuts is gradually tightened to slowly compress the springs 126 and safely draw the casings 106 and 108 and the spacer 102 together. Three or four such rods (e.g., the rod 114) may be used to initially compress the springs 126 and assemble the casing 104. However, more or fewer threaded rods could be used instead. Alternatively, the threaded rods (e.g., the rod 114) and the counter-tightened nuts (e.g., the nuts 116 and 118) could instead be bolts having an appropriate length. However, extended length bolts may be difficult to obtain and/or cost prohibitive in comparison to threaded rods. In any event, once the casings 106 and 108 and the spacer 102 have been initially assembled using the threaded rods (e.g., the threaded rod 114), relatively shorter bolts (e.g., the bolt 110) can then be used to complete the assembly of the casing 104. For example, four or five such bolts may be used in addition to the threaded rods to secure the casings 106 and 106 to the spacer 102.
Disassembly of the casing 104 can be safely accomplished by first removing the relatively shorter bolts (e.g., the bolt 110) and then slowly removing the threaded rods (e.g., the rod 114) by loosening their respective nuts (e.g., the nut 120) in a synchronized manner to gradually relieve the compression or pre-load of the springs 126. Once the nuts (e.g., the nut 120) reach the ends (e.g., the end 148) of their respective rods (e.g., the rod 114), the springs 126 are substantially uncompressed and the rods and the casing 106 can be removed from the actuator 100 to enable, for example, the actuator to be serviced (e.g., to replace the diaphragm 128).
While the example actuator 100 enables safe assembly and disassembly (e.g., in the field) of the casing 104, the configuration shown in
Turing in more detail to the example ring-shaped or cylindrically-shaped spacer 200, the partially threaded apertures 204-218 are circumferentially spaced about a central opening or longitudinal passage 220 defined by the spacer 200. More specifically, in the example of
The apertures 204-218 are partially threaded so that a portion of each of the apertures 204-218 near or adjacent either the first circumferential surface 222 or the second circumferential surface 224 is threaded and the remaining portion is not threaded and, thus, functions to provide passage or clearance to a threaded fastener (e.g., a bolt, threaded rod, etc.). As depicted in the example of
To assemble the example actuator 100 using the example one-piece or unitary spacer 200 instead of the example multi-piece spacer 102, one of the first or second circumferential surfaces 222 and 224 is disposed on the lower casing 108. Threaded bolts (e.g., such as the threaded bolt 110) are then threaded into the apertures having threaded portions adjacent to the one of the circumferential surfaces 222 and 224 that is in contact with the lower casing 108. For example, if the first circumferential surface 222 is in contact with the lower casing 108, threaded bolts are threaded into the apertures 206, 210, 214, and 218 until the spacer 200 is securely engaged with lower casing 108. The springs 126 and other components of the actuator 100 are assembled into the lower casing 108 and the upper casing 106, the diaphragm 128, and the upper spring plate 122 are placed on springs 126. Threaded bolts (e.g., the threaded bolt 110) are then passed through clearance holes (not shown) in the upper casing 106 and into the ones of the apertures 204-218 having threaded portions adjacent to the one of the circumferential surfaces 222 and 224 facing the upper casing 106. Continuing with the above example in which the first circumferential surface 222 is in contact with the lower casing 108, threaded bolts are passed through the upper casing 106 into the apertures 204, 208, 212, and 216. The threaded bolts engaging the apertures 204, 208, 212, and 216 are then tightened (e.g., in an alternating sequence) to slowly and evenly draw the upper casing 106, the diaphragm 128, and the spring plate 122 toward the lower casing 108 to safely compress the springs 126 and secure the upper casing 106 to the spacer 200. Additionally, although not shown, additional nuts could be counter-tightened (i.e., to function as lock nuts) against the nuts (e.g., the nut 112).
Disassembly of the example actuator 100 incorporating the example spacer 200 can also be accomplished in a safe manner. In particular, the threaded bolts extending through the upper casing 106 into the apertures 204, 208, 212, and 216 are slowly loosened (e.g., in an alternating pattern or sequence) to allow the upper casing 106 to separate from the spacer 200 and to allow the springs 126 to decompress. The threaded bolts used with the apertures 204, 208, 212, and 216 have sufficient lengths so that the springs 126 are substantially or fully decompressed before the threads of the threaded bolts are no longer engaged with the threads of the apertures 204, 208, 212, and 216. As a result, the upper casing 106 can be removed (e.g., in the field) without the risk of a sudden, potentially unsafe, release of spring energy.
As can be appreciated from the foregoing, the example spacer 200 provides fastener engagements (e.g., threads) nearer to the upper and lower casings 106 and 108 and, thus, eliminates the need to use the relatively longer threaded rods or bolts (e.g., the threaded rod 114) that are needed when the example spacer 102 is used. In this manner, the example spacer 200 enables the example actuator 100 to be safely assembled and disassembled using relatively shorter threaded bolts (e.g., such as the threaded bolt 110). Such relatively shorter threaded bolts may also eliminate the relatively long protrusions associated with the threaded rod shown in
The example spacers 102, 200, and 300 described above form part of the actuator casing (e.g., spring casing) and substantially encase or hide the fasteners (e.g., the threaded bolt 110) used to assemble the upper and lower casings to the spacer. However, the example spacer 102 of
While all of the example spacers 102, 200, and 300 substantially encase or hide fasteners used to assemble actuator casings to the spacers, the example spacers 200 and 300 also enable relatively shorter threaded bolts to be used for all of the casing fasteners (i.e., do not require the use of relatively long sections of threaded rod). As a result, use of the example spacers 200 and 300 results in a substantial reduction in the degree to which the ends of the threaded fasteners protrude from the casing(s). In some examples, the threaded fasteners may be sized so that their ends are substantially flush or recessed and, thus, result in no protrusion from the casing(s).
In contrast to the example spacers 102, 200, and 300, the example spacer 500 has outwardly projecting flanges 504 and 506 and, thus, substantially exposes (to the environment external to the actuator casing 104) the threaded fasteners used to assemble the casings 106 and 108 to the spacer 500. Exposure of the fasteners in this manner may facilitate field replacement of the fasteners in the event that a fastener becomes damaged, weakened (e.g., via corrosion), or otherwise requires replacement.
The example spacers 102, 200, 300, and 500 described above may be made substantially of metal(s) using a machining process, a casting process, and/or a forging process. In the case of the example spacers 300 and 500, the flanges 304, 306, 504, and 506 may be separately fabricated from, for example, metal plate and attached (e.g., via welding) to a cylindrical structure (e.g., a piece of pipe) to form a substantially unitary or one-piece ring-shaped structure. Alternatively, the example spacers 300 and 500 could be partially formed using a casting or forging process and then machined to a finished form or may be formed by machining a solid block of metal, thereby eliminating the need to separately fabricate and attach flanges. In other words, the flanges may be integrally formed with the finished spacer to eliminate the need for additional fabrication and processing associated with separately formed flanges. Additionally, the threaded apertures used in the example spacers 102, 200, 300, and 500 may be tapped threads, thread inserts such as helicoil inserts, or may be implemented using any other process and/or device that provides internal threads.
The example spacer 600 also includes a plurality of cylinder-like projections 610 that are circumferentially spaced about the opening and which project inwardly toward the opening 604. The projections 610 have bores or passages therethrough for receiving a respective plurality of threaded metal inserts (two of which are indicated at reference numerals 612 and 614). The threaded metal inserts 612 and 614 are preferably, but not necessarily, removably inserted into the bores or passages in the projections 610 after the body 602 has been fabricated (e.g., injection molded). In this manner, one or more of the threaded metal inserts 612 and 614 can be replaced, if needed, to repair the spacer 600. Additionally, the body 602 and the inserts 612 and 614 are sized so that a substantial portion of the compressive forces to which the spacer 600 is subject when assembled within the casing 104 is transmitted through the metal inserts 612 and 614. As a result, the compressive forces experienced by the plastic body 602 are substantially reduced to prevent deformation or damage to the spacer 600.
An example threaded metal insert 700 shown in
Although certain apparatus, methods, and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. To the contrary, this patent covers all embodiments fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3064685||Feb 15, 1960||Nov 20, 1962||Howard Washnock Donald||Diaphragm housing|
|US3385172||Mar 31, 1966||May 28, 1968||Sylvan James Kaminga||Detachably ganged variable capacity cylinder construction|
|US3571883 *||Apr 19, 1968||Mar 23, 1971||Westinghouse Air Brake Co||Method of making a fluid operated cylinder device|
|US3838630 *||Mar 30, 1973||Oct 1, 1974||J Kobelt||Double-acting positioning linear actuator|
|US4522111||Sep 13, 1982||Jun 11, 1985||Jacob Kobelt||Double-acting, fluid actuated positioning actuator|
|US5167182||Oct 4, 1991||Dec 1, 1992||Sims James O||Modular fluid actuator|
|US6840154 *||Jun 15, 2002||Jan 11, 2005||Festo Ag & Co.||Working cylinder|
|US20030172806||Jun 15, 2002||Sep 18, 2003||Uwe Modinger||Working cylinder|
|1||International Search Report Corresponding to International Application PCT/US2007/000865 mailed Jun. 6, 2007, 5 pages.|
|2||Written Opinion of the International Searching Authority Corresponding to International Application PCT/US2007/000865 mailed Jun. 6, 2007, 6 pages.|
|U.S. Classification||92/171.1, 92/94, 29/888.06|
|International Classification||F01B19/00, B23P11/00|
|Cooperative Classification||Y10T29/4927, F15B15/1428, F15B15/10|
|European Classification||F15B15/10, F15B15/14E2|
|Jan 20, 2006||AS||Assignment|
Owner name: FISHER CONTROLS INTERNATIONAL LLC, IOWA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SOULIERE, ERNEST GEORGE;BLADE, KENNETH ALAN;REEL/FRAME:017501/0840
Effective date: 20060120
|Jul 22, 2008||AS||Assignment|
Owner name: FISHER CONTROLS INTERNATIONAL LLC, IOWA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:O HARA, DENNIS E.;REEL/FRAME:022610/0655
Effective date: 20041116
|Sep 19, 2011||FPAY||Fee payment|
Year of fee payment: 4
|Oct 29, 2015||FPAY||Fee payment|
Year of fee payment: 8